Materials Literature
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The geometries and binding energies of the most stable isomers of nickel, silver, and gold nanoclusters of size 6, 7, 12, 13, 14, 19, 38, 55, and 75 atoms, predicted with an n-body Gupta potential, are presented. An exhaustive search for low-energy minima on the potential energy surface was carried out using an evolut…
Electron dynamics in gold nanoparticles with an average diameter between 9 and 48 nm have been studied by femtosecond transient absorption spectroscopy. Following the plasmon bleach recovery after low power excitation indicates that a non-Fermi electron distribution thermalizes by electron–electron relaxation on a tim…
The relaxation of the $1P$ to $1S$ electronic states of CdSe semiconductor nanocrystals is followed by infrared pump-probe spectroscopy. Fast (1 ps) and slow (>200 ps) components are observed. Using different capping molecules to control the hole states, we show how the intraband relaxation slows down as the hole i…
Highly crystalline, size-selected silicon (Si) nanocrystals in the size range 2--10 nm were grown in inverse micelles and their optical absorption and photoluminescence (PL) properties were studied. High resolution TEM and electron diffraction results show that these nanocrystals retain their cubic diamond structures…
The emission and reflection spectra of ZnO have been investigated in the intrinsic region and the data have been interpreted in terms of the wurtzite crystal band structure. Free-exciton emission is observed for the first time. Both the ${\ensuremath{\Gamma}}_{5}$ and ${\ensuremath{\Gamma}}_{6}$ state excitons associa…
If deposited on a hydrophobic rough substrate, a small drop of water can look like a pearl, with a contact angle close to 180°. We examine the conditions for observing such a phenomenon and show practical achievements where the contact angle can be predicted and thus quantitatively tuned by the design of the surface m…
Formation of the scutes and dermis of the embryonic shell of the turtle Emydura macquarii was studied using light and electron microscopy. Shell morphogenesis begins at embryonic stage 15 and the shape of the shell is mostly completed by embryonic stage 19. The carapace anlagen arises as a thickening of the skin in th…
The synthesis and characterization of 4,4‘-dinonyl-2,2‘-bisoxazole (NBO) and its oligomers are described. The optical, electronic, and structural properties of these oligomers, NBO, NBO 2, and NBO 3, are compared to their sulfur analogues (NBT, NBT 2, and NBT 3 ). In the series (NBO) n and (NBT) n, there is a red shif…
It had long ago been reported that poppy acid crystals encapsulate and orient a great variety of molecules during solution growth and in so doing seem to egregiously violate the principle of isomorphism. To comprehend this surprising host−guest chemistry, and exploit it for measuring anisotropic molecular properties,…
A versatile and generally applicable synthetic method for making second-order nonlinear optical (NLO) side-chain aromatic polyquinolines has been developed. This approach emphasizes the ease of incorporating NLO chromophores onto the pendent phenyl moieties of parent polyquinolines at the final stage via a mild Mitsun…
For Pd clusters on γ-Al 2 O 3 epitaxially grown on NiAl(110) the lattice constant has been determined as a function of the cluster size by evaluating patterns induced by double diffraction involving the NiAl substrate and the cluster lattice. Similar to results reported previously for platinum and tantalum clusters on…
The pyrolysis of poly(silylenemethylene) (PSE), [SiH 2 CH 2 ] n, a linear polycarbosilane with a regularly alternating Si−C backbone structure and a high-yield precursor to stoichiometric SiC, was investigated by using a combination of thermogravimetric analysis, evolved gas analysis, and solid-state NMR and IR spectr…
A new series of Mg II Al III Sn IV hydrotalcite (HT)-like layered double hydroxides (LDHs) with Mg:Al:Sn = 3:1:0 to 3:0:1 were synthesized for the first time by a simple coprecipitation method at room temperature. The physicochemical properties of both as-synthesized and their thermally decomposed products were invest…
The atomic and electronic structures of three Li x V 2 O 5 phases have been investigated using plane wave calculations based on density functional theory. We show that reduction of the vanadium ions occurs during lithium intercalation. At low lithium concentrations this reduction is limited to specific ions. Changes t…
The delicate interplay between plasmonic excitations and interband transitions in noble metals is described by means of {\it ab initio} calculations and a simple model in which the conduction electron plasmon is coupled to the continuum of electron-hole pairs. Band structure effects, specially the energy at which the…
A sensitive mid-infrared (MIR, 900-1100 cm-1, 112-136 meV) photo-elastic polarization modulation technique is used to measure simultaneously Faraday rotation and circular dichroism in thin metal films. These two quantities determine the complex AC Hall conductivity. This novel technique is applied to study Au and Cu t…
We consider the case when a supercritical fluid emerges at sonic speed from a small orifice in a high pressure chamber. The subsequent expansion causes a pressure drop and the fluid then enters a regime where its equation of state in $P-V$ space becomes concave towards the origin. This is the signal for an expansion s…
The heterogeneous reactivity of gaseous nitrogen dioxide on mineral oxide particles was investigated. In particular, spectroscopic and kinetic measurements have been made to investigate surface reactions of NO 2 on Al 2 O 3, Fe 2 O 3, and TiO 2 at 298 K. Both gas-phase and surface-bound products are formed from the re…
A simplified and rapid procedure for the determination of pyroglutamic acid in peptides was developed. The method involves the enzymatic cleavage of an N-terminal pyroglutamate residue using a thermostable pyroglutamate aminopeptidase and isocratic HPLC separation of the resulting enzymatic hydrolysate using a column…
The alpha subunit of tryptophan synthase (alphaTS) from Escherichia coli is a 268-residue 8-stranded beta/alpha barrel protein. Two autonomous folding units, comprising the first six strands (residues 1-188) and the last two strands (residues 189-268), have been previously identified in this single structural domain p…